Conventionally, in a transfer roller disposed in an image forming apparatus such as a copy machine, a difference in thermal expansion coefficient between members constituting the transfer roller may cause a shift of an axial position of a flange. The shift of the axial position of the flange in the transfer roller cause a shift of an axial position of a rib formed on a transfer belt that is stretched around the transfer roller. This may cause a problem with restriction of meandering of the transfer belt.
To solve the above-described problem, various roller devices have been proposed. For example, the following roller device is disclosed (for example, see Patent Literature 1). The roller device presses a roller that restricts a position of an intermediate transfer belt toward the driven roller via a washer with a wave washer spring, a snap ring, and a similar member at a predetermined pressure. For example, the following roller device is also disclosed (for example, see Patent Literature 2). The roller device biases a belt guide member, which restricts a position of an intermediate transfer belt, in a direction where the belt guide member is consistently pressed toward an end surface of a roller by a spring.